Not in and of itself. But if rank is granted by someone who is credentialed to grant rank, and that person in turn is responsible to a teacher or a federation for upholding certain standards, and you consider those standards worthwhile, there can be. It's a quality control thing, sort of.

In theory, of course that's true. In practice, there really is very little in the way of standards and quality control.

Overall, ranks probably end up causing more problems than they solve.

Ideally, there probably ought to be none - but that route's probably hard going knowing human nature. It also takes away pretty much the only leash that an organization has on its members - which is the real reason why rank's not going anywhere soon.